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701 lines
20 KiB
C
701 lines
20 KiB
C
/*
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* QEMU RISC-V PMP (Physical Memory Protection)
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*
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* Author: Daire McNamara, daire.mcnamara@emdalo.com
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* Ivan Griffin, ivan.griffin@emdalo.com
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*
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* This provides a RISC-V Physical Memory Protection implementation
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2 or later, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "qemu/osdep.h"
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#include "qemu/log.h"
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#include "qapi/error.h"
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#include "cpu.h"
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#include "trace.h"
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#include "exec/exec-all.h"
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#include "exec/page-protection.h"
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static bool pmp_write_cfg(CPURISCVState *env, uint32_t addr_index,
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uint8_t val);
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static uint8_t pmp_read_cfg(CPURISCVState *env, uint32_t addr_index);
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/*
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* Accessor method to extract address matching type 'a field' from cfg reg
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*/
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static inline uint8_t pmp_get_a_field(uint8_t cfg)
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{
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uint8_t a = cfg >> 3;
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return a & 0x3;
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}
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/*
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* Check whether a PMP is locked or not.
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*/
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static inline int pmp_is_locked(CPURISCVState *env, uint32_t pmp_index)
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{
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/* mseccfg.RLB is set */
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if (MSECCFG_RLB_ISSET(env)) {
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return 0;
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}
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if (env->pmp_state.pmp[pmp_index].cfg_reg & PMP_LOCK) {
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return 1;
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}
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/* Top PMP has no 'next' to check */
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if ((pmp_index + 1u) >= MAX_RISCV_PMPS) {
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return 0;
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}
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return 0;
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}
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/*
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* Count the number of active rules.
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*/
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uint32_t pmp_get_num_rules(CPURISCVState *env)
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{
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return env->pmp_state.num_rules;
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}
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/*
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* Accessor to get the cfg reg for a specific PMP/HART
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*/
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static inline uint8_t pmp_read_cfg(CPURISCVState *env, uint32_t pmp_index)
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{
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if (pmp_index < MAX_RISCV_PMPS) {
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return env->pmp_state.pmp[pmp_index].cfg_reg;
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}
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return 0;
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}
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/*
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* Accessor to set the cfg reg for a specific PMP/HART
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* Bounds checks and relevant lock bit.
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*/
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static bool pmp_write_cfg(CPURISCVState *env, uint32_t pmp_index, uint8_t val)
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{
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if (pmp_index < MAX_RISCV_PMPS) {
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bool locked = true;
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if (riscv_cpu_cfg(env)->ext_smepmp) {
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/* mseccfg.RLB is set */
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if (MSECCFG_RLB_ISSET(env)) {
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locked = false;
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}
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/* mseccfg.MML is not set */
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if (!MSECCFG_MML_ISSET(env) && !pmp_is_locked(env, pmp_index)) {
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locked = false;
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}
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/* mseccfg.MML is set */
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if (MSECCFG_MML_ISSET(env)) {
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/* not adding execute bit */
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if ((val & PMP_LOCK) != 0 && (val & PMP_EXEC) != PMP_EXEC) {
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locked = false;
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}
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/* shared region and not adding X bit */
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if ((val & PMP_LOCK) != PMP_LOCK &&
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(val & 0x7) != (PMP_WRITE | PMP_EXEC)) {
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locked = false;
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}
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}
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} else {
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if (!pmp_is_locked(env, pmp_index)) {
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locked = false;
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}
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}
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if (locked) {
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qemu_log_mask(LOG_GUEST_ERROR, "ignoring pmpcfg write - locked\n");
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} else if (env->pmp_state.pmp[pmp_index].cfg_reg != val) {
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/* If !mseccfg.MML then ignore writes with encoding RW=01 */
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if ((val & PMP_WRITE) && !(val & PMP_READ) &&
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!MSECCFG_MML_ISSET(env)) {
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return false;
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}
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env->pmp_state.pmp[pmp_index].cfg_reg = val;
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pmp_update_rule_addr(env, pmp_index);
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return true;
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}
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} else {
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qemu_log_mask(LOG_GUEST_ERROR,
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"ignoring pmpcfg write - out of bounds\n");
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}
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return false;
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}
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void pmp_unlock_entries(CPURISCVState *env)
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{
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uint32_t pmp_num = pmp_get_num_rules(env);
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int i;
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for (i = 0; i < pmp_num; i++) {
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env->pmp_state.pmp[i].cfg_reg &= ~(PMP_LOCK | PMP_AMATCH);
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}
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}
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static void pmp_decode_napot(hwaddr a, hwaddr *sa, hwaddr *ea)
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{
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/*
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* aaaa...aaa0 8-byte NAPOT range
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* aaaa...aa01 16-byte NAPOT range
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* aaaa...a011 32-byte NAPOT range
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* ...
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* aa01...1111 2^XLEN-byte NAPOT range
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* a011...1111 2^(XLEN+1)-byte NAPOT range
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* 0111...1111 2^(XLEN+2)-byte NAPOT range
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* 1111...1111 Reserved
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*/
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a = (a << 2) | 0x3;
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*sa = a & (a + 1);
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*ea = a | (a + 1);
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}
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void pmp_update_rule_addr(CPURISCVState *env, uint32_t pmp_index)
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{
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uint8_t this_cfg = env->pmp_state.pmp[pmp_index].cfg_reg;
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target_ulong this_addr = env->pmp_state.pmp[pmp_index].addr_reg;
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target_ulong prev_addr = 0u;
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hwaddr sa = 0u;
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hwaddr ea = 0u;
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if (pmp_index >= 1u) {
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prev_addr = env->pmp_state.pmp[pmp_index - 1].addr_reg;
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}
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switch (pmp_get_a_field(this_cfg)) {
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case PMP_AMATCH_OFF:
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sa = 0u;
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ea = -1;
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break;
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case PMP_AMATCH_TOR:
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sa = prev_addr << 2; /* shift up from [xx:0] to [xx+2:2] */
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ea = (this_addr << 2) - 1u;
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if (sa > ea) {
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sa = ea = 0u;
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}
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break;
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case PMP_AMATCH_NA4:
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sa = this_addr << 2; /* shift up from [xx:0] to [xx+2:2] */
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ea = (sa + 4u) - 1u;
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break;
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case PMP_AMATCH_NAPOT:
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pmp_decode_napot(this_addr, &sa, &ea);
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break;
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default:
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sa = 0u;
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ea = 0u;
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break;
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}
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env->pmp_state.addr[pmp_index].sa = sa;
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env->pmp_state.addr[pmp_index].ea = ea;
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}
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void pmp_update_rule_nums(CPURISCVState *env)
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{
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int i;
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env->pmp_state.num_rules = 0;
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for (i = 0; i < MAX_RISCV_PMPS; i++) {
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const uint8_t a_field =
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pmp_get_a_field(env->pmp_state.pmp[i].cfg_reg);
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if (PMP_AMATCH_OFF != a_field) {
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env->pmp_state.num_rules++;
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}
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}
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}
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static int pmp_is_in_range(CPURISCVState *env, int pmp_index, hwaddr addr)
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{
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int result = 0;
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if ((addr >= env->pmp_state.addr[pmp_index].sa) &&
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(addr <= env->pmp_state.addr[pmp_index].ea)) {
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result = 1;
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} else {
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result = 0;
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}
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return result;
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}
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/*
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* Check if the address has required RWX privs when no PMP entry is matched.
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*/
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static bool pmp_hart_has_privs_default(CPURISCVState *env, pmp_priv_t privs,
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pmp_priv_t *allowed_privs,
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target_ulong mode)
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{
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bool ret;
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if (MSECCFG_MMWP_ISSET(env)) {
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/*
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* The Machine Mode Whitelist Policy (mseccfg.MMWP) is set
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* so we default to deny all, even for M-mode.
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*/
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*allowed_privs = 0;
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return false;
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} else if (MSECCFG_MML_ISSET(env)) {
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/*
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* The Machine Mode Lockdown (mseccfg.MML) bit is set
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* so we can only execute code in M-mode with an applicable
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* rule. Other modes are disabled.
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*/
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if (mode == PRV_M && !(privs & PMP_EXEC)) {
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ret = true;
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*allowed_privs = PMP_READ | PMP_WRITE;
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} else {
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ret = false;
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*allowed_privs = 0;
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}
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return ret;
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}
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if (!riscv_cpu_cfg(env)->pmp || (mode == PRV_M)) {
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/*
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* Privileged spec v1.10 states if HW doesn't implement any PMP entry
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* or no PMP entry matches an M-Mode access, the access succeeds.
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*/
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ret = true;
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*allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC;
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} else {
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/*
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* Other modes are not allowed to succeed if they don't * match a rule,
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* but there are rules. We've checked for no rule earlier in this
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* function.
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*/
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ret = false;
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*allowed_privs = 0;
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}
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return ret;
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}
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/*
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* Public Interface
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*/
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/*
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* Check if the address has required RWX privs to complete desired operation
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* Return true if a pmp rule match or default match
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* Return false if no match
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*/
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bool pmp_hart_has_privs(CPURISCVState *env, hwaddr addr,
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target_ulong size, pmp_priv_t privs,
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pmp_priv_t *allowed_privs, target_ulong mode)
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{
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int i = 0;
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int pmp_size = 0;
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hwaddr s = 0;
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hwaddr e = 0;
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/* Short cut if no rules */
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if (0 == pmp_get_num_rules(env)) {
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return pmp_hart_has_privs_default(env, privs, allowed_privs, mode);
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}
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if (size == 0) {
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if (riscv_cpu_cfg(env)->mmu) {
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/*
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* If size is unknown (0), assume that all bytes
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* from addr to the end of the page will be accessed.
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*/
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pmp_size = -(addr | TARGET_PAGE_MASK);
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} else {
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pmp_size = 2 << riscv_cpu_mxl(env);
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}
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} else {
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pmp_size = size;
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}
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/*
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* 1.10 draft priv spec states there is an implicit order
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* from low to high
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*/
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for (i = 0; i < MAX_RISCV_PMPS; i++) {
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s = pmp_is_in_range(env, i, addr);
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e = pmp_is_in_range(env, i, addr + pmp_size - 1);
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/* partially inside */
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if ((s + e) == 1) {
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qemu_log_mask(LOG_GUEST_ERROR,
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"pmp violation - access is partially inside\n");
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*allowed_privs = 0;
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return false;
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}
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/* fully inside */
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const uint8_t a_field =
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pmp_get_a_field(env->pmp_state.pmp[i].cfg_reg);
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/*
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* Convert the PMP permissions to match the truth table in the
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* Smepmp spec.
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*/
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const uint8_t smepmp_operation =
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((env->pmp_state.pmp[i].cfg_reg & PMP_LOCK) >> 4) |
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((env->pmp_state.pmp[i].cfg_reg & PMP_READ) << 2) |
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(env->pmp_state.pmp[i].cfg_reg & PMP_WRITE) |
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((env->pmp_state.pmp[i].cfg_reg & PMP_EXEC) >> 2);
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if (((s + e) == 2) && (PMP_AMATCH_OFF != a_field)) {
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/*
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* If the PMP entry is not off and the address is in range,
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* do the priv check
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*/
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if (!MSECCFG_MML_ISSET(env)) {
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/*
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* If mseccfg.MML Bit is not set, do pmp priv check
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* This will always apply to regular PMP.
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*/
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*allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC;
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if ((mode != PRV_M) || pmp_is_locked(env, i)) {
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*allowed_privs &= env->pmp_state.pmp[i].cfg_reg;
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}
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} else {
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/*
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* If mseccfg.MML Bit set, do the enhanced pmp priv check
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*/
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if (mode == PRV_M) {
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switch (smepmp_operation) {
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case 0:
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case 1:
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case 4:
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case 5:
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case 6:
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case 7:
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case 8:
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*allowed_privs = 0;
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break;
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case 2:
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case 3:
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case 14:
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*allowed_privs = PMP_READ | PMP_WRITE;
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break;
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case 9:
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case 10:
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*allowed_privs = PMP_EXEC;
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break;
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case 11:
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case 13:
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*allowed_privs = PMP_READ | PMP_EXEC;
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break;
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case 12:
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case 15:
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*allowed_privs = PMP_READ;
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break;
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default:
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g_assert_not_reached();
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}
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} else {
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switch (smepmp_operation) {
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case 0:
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case 8:
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case 9:
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case 12:
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case 13:
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case 14:
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*allowed_privs = 0;
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break;
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case 1:
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case 10:
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case 11:
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*allowed_privs = PMP_EXEC;
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break;
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case 2:
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case 4:
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case 15:
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*allowed_privs = PMP_READ;
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break;
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case 3:
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case 6:
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*allowed_privs = PMP_READ | PMP_WRITE;
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break;
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case 5:
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*allowed_privs = PMP_READ | PMP_EXEC;
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break;
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case 7:
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*allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC;
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break;
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default:
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g_assert_not_reached();
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}
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}
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}
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/*
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* If matching address range was found, the protection bits
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* defined with PMP must be used. We shouldn't fallback on
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* finding default privileges.
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*/
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return (privs & *allowed_privs) == privs;
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}
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}
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/* No rule matched */
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return pmp_hart_has_privs_default(env, privs, allowed_privs, mode);
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}
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/*
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* Handle a write to a pmpcfg CSR
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*/
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void pmpcfg_csr_write(CPURISCVState *env, uint32_t reg_index,
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target_ulong val)
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{
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int i;
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uint8_t cfg_val;
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int pmpcfg_nums = 2 << riscv_cpu_mxl(env);
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bool modified = false;
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trace_pmpcfg_csr_write(env->mhartid, reg_index, val);
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for (i = 0; i < pmpcfg_nums; i++) {
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cfg_val = (val >> 8 * i) & 0xff;
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modified |= pmp_write_cfg(env, (reg_index * 4) + i, cfg_val);
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}
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/* If PMP permission of any addr has been changed, flush TLB pages. */
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if (modified) {
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pmp_update_rule_nums(env);
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tlb_flush(env_cpu(env));
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}
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}
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/*
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* Handle a read from a pmpcfg CSR
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*/
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target_ulong pmpcfg_csr_read(CPURISCVState *env, uint32_t reg_index)
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{
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int i;
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target_ulong cfg_val = 0;
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target_ulong val = 0;
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int pmpcfg_nums = 2 << riscv_cpu_mxl(env);
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for (i = 0; i < pmpcfg_nums; i++) {
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val = pmp_read_cfg(env, (reg_index * 4) + i);
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cfg_val |= (val << (i * 8));
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}
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trace_pmpcfg_csr_read(env->mhartid, reg_index, cfg_val);
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return cfg_val;
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}
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/*
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* Handle a write to a pmpaddr CSR
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*/
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void pmpaddr_csr_write(CPURISCVState *env, uint32_t addr_index,
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target_ulong val)
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{
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trace_pmpaddr_csr_write(env->mhartid, addr_index, val);
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bool is_next_cfg_tor = false;
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if (addr_index < MAX_RISCV_PMPS) {
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/*
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* In TOR mode, need to check the lock bit of the next pmp
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|
* (if there is a next).
|
|
*/
|
|
if (addr_index + 1 < MAX_RISCV_PMPS) {
|
|
uint8_t pmp_cfg = env->pmp_state.pmp[addr_index + 1].cfg_reg;
|
|
is_next_cfg_tor = PMP_AMATCH_TOR == pmp_get_a_field(pmp_cfg);
|
|
|
|
if (pmp_cfg & PMP_LOCK && is_next_cfg_tor) {
|
|
qemu_log_mask(LOG_GUEST_ERROR,
|
|
"ignoring pmpaddr write - pmpcfg + 1 locked\n");
|
|
return;
|
|
}
|
|
}
|
|
|
|
if (!pmp_is_locked(env, addr_index)) {
|
|
if (env->pmp_state.pmp[addr_index].addr_reg != val) {
|
|
env->pmp_state.pmp[addr_index].addr_reg = val;
|
|
pmp_update_rule_addr(env, addr_index);
|
|
if (is_next_cfg_tor) {
|
|
pmp_update_rule_addr(env, addr_index + 1);
|
|
}
|
|
tlb_flush(env_cpu(env));
|
|
}
|
|
} else {
|
|
qemu_log_mask(LOG_GUEST_ERROR,
|
|
"ignoring pmpaddr write - locked\n");
|
|
}
|
|
} else {
|
|
qemu_log_mask(LOG_GUEST_ERROR,
|
|
"ignoring pmpaddr write - out of bounds\n");
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
* Handle a read from a pmpaddr CSR
|
|
*/
|
|
target_ulong pmpaddr_csr_read(CPURISCVState *env, uint32_t addr_index)
|
|
{
|
|
target_ulong val = 0;
|
|
|
|
if (addr_index < MAX_RISCV_PMPS) {
|
|
val = env->pmp_state.pmp[addr_index].addr_reg;
|
|
trace_pmpaddr_csr_read(env->mhartid, addr_index, val);
|
|
} else {
|
|
qemu_log_mask(LOG_GUEST_ERROR,
|
|
"ignoring pmpaddr read - out of bounds\n");
|
|
}
|
|
|
|
return val;
|
|
}
|
|
|
|
/*
|
|
* Handle a write to a mseccfg CSR
|
|
*/
|
|
void mseccfg_csr_write(CPURISCVState *env, target_ulong val)
|
|
{
|
|
int i;
|
|
|
|
trace_mseccfg_csr_write(env->mhartid, val);
|
|
|
|
/* RLB cannot be enabled if it's already 0 and if any regions are locked */
|
|
if (!MSECCFG_RLB_ISSET(env)) {
|
|
for (i = 0; i < MAX_RISCV_PMPS; i++) {
|
|
if (pmp_is_locked(env, i)) {
|
|
val &= ~MSECCFG_RLB;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (riscv_cpu_cfg(env)->ext_smepmp) {
|
|
/* Sticky bits */
|
|
val |= (env->mseccfg & (MSECCFG_MMWP | MSECCFG_MML));
|
|
if ((val ^ env->mseccfg) & (MSECCFG_MMWP | MSECCFG_MML)) {
|
|
tlb_flush(env_cpu(env));
|
|
}
|
|
} else {
|
|
val &= ~(MSECCFG_MMWP | MSECCFG_MML | MSECCFG_RLB);
|
|
}
|
|
|
|
/* M-mode forward cfi to be enabled if cfi extension is implemented */
|
|
if (env_archcpu(env)->cfg.ext_zicfilp) {
|
|
val |= (val & MSECCFG_MLPE);
|
|
}
|
|
|
|
env->mseccfg = val;
|
|
}
|
|
|
|
/*
|
|
* Handle a read from a mseccfg CSR
|
|
*/
|
|
target_ulong mseccfg_csr_read(CPURISCVState *env)
|
|
{
|
|
trace_mseccfg_csr_read(env->mhartid, env->mseccfg);
|
|
return env->mseccfg;
|
|
}
|
|
|
|
/*
|
|
* Calculate the TLB size.
|
|
* It's possible that PMP regions only cover partial of the TLB page, and
|
|
* this may split the page into regions with different permissions.
|
|
* For example if PMP0 is (0x80000008~0x8000000F, R) and PMP1 is (0x80000000
|
|
* ~0x80000FFF, RWX), then region 0x80000008~0x8000000F has R permission, and
|
|
* the other regions in this page have RWX permissions.
|
|
* A write access to 0x80000000 will match PMP1. However we cannot cache the
|
|
* translation result in the TLB since this will make the write access to
|
|
* 0x80000008 bypass the check of PMP0.
|
|
* To avoid this we return a size of 1 (which means no caching) if the PMP
|
|
* region only covers partial of the TLB page.
|
|
*/
|
|
target_ulong pmp_get_tlb_size(CPURISCVState *env, hwaddr addr)
|
|
{
|
|
hwaddr pmp_sa;
|
|
hwaddr pmp_ea;
|
|
hwaddr tlb_sa = addr & ~(TARGET_PAGE_SIZE - 1);
|
|
hwaddr tlb_ea = tlb_sa + TARGET_PAGE_SIZE - 1;
|
|
int i;
|
|
|
|
/*
|
|
* If PMP is not supported or there are no PMP rules, the TLB page will not
|
|
* be split into regions with different permissions by PMP so we set the
|
|
* size to TARGET_PAGE_SIZE.
|
|
*/
|
|
if (!riscv_cpu_cfg(env)->pmp || !pmp_get_num_rules(env)) {
|
|
return TARGET_PAGE_SIZE;
|
|
}
|
|
|
|
for (i = 0; i < MAX_RISCV_PMPS; i++) {
|
|
if (pmp_get_a_field(env->pmp_state.pmp[i].cfg_reg) == PMP_AMATCH_OFF) {
|
|
continue;
|
|
}
|
|
|
|
pmp_sa = env->pmp_state.addr[i].sa;
|
|
pmp_ea = env->pmp_state.addr[i].ea;
|
|
|
|
/*
|
|
* Only the first PMP entry that covers (whole or partial of) the TLB
|
|
* page really matters:
|
|
* If it covers the whole TLB page, set the size to TARGET_PAGE_SIZE,
|
|
* since the following PMP entries have lower priority and will not
|
|
* affect the permissions of the page.
|
|
* If it only covers partial of the TLB page, set the size to 1 since
|
|
* the allowed permissions of the region may be different from other
|
|
* region of the page.
|
|
*/
|
|
if (pmp_sa <= tlb_sa && pmp_ea >= tlb_ea) {
|
|
return TARGET_PAGE_SIZE;
|
|
} else if ((pmp_sa >= tlb_sa && pmp_sa <= tlb_ea) ||
|
|
(pmp_ea >= tlb_sa && pmp_ea <= tlb_ea)) {
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If no PMP entry matches the TLB page, the TLB page will also not be
|
|
* split into regions with different permissions by PMP so we set the size
|
|
* to TARGET_PAGE_SIZE.
|
|
*/
|
|
return TARGET_PAGE_SIZE;
|
|
}
|
|
|
|
/*
|
|
* Convert PMP privilege to TLB page privilege.
|
|
*/
|
|
int pmp_priv_to_page_prot(pmp_priv_t pmp_priv)
|
|
{
|
|
int prot = 0;
|
|
|
|
if (pmp_priv & PMP_READ) {
|
|
prot |= PAGE_READ;
|
|
}
|
|
if (pmp_priv & PMP_WRITE) {
|
|
prot |= PAGE_WRITE;
|
|
}
|
|
if (pmp_priv & PMP_EXEC) {
|
|
prot |= PAGE_EXEC;
|
|
}
|
|
|
|
return prot;
|
|
}
|